10:1 Cycloid Helicopter Gearbox

It's always cycloids with me lately, isn't it?

This is my second attempt at making a gearbox which fits motors from a
crashed RC heli, the first which works acceptably: Note I do not say fly
as much as "whirl its blades around alarmingly". Unlike my previous
attempts it has no preferred direction of rotation. It cannot be
backdriven -- if you try and let the motor freewheel, it will just
seize!